One known method for correcting varus (bowlegged) or valgus (knock-kneed) deformities in the tibia includes removing a wedge-shaped segment of the tibia extending generally transversely almost completely across the tibia just below the knee joint, bending the tibia to close the space left by removal of the segment, fastening the tibia in its bent position and allowing the bone to heal in that position. Such a method, if properly done, can relieve painful knee conditions caused by disproportionate loading of one side of the knee joint due to such deformities. Achieving the proper orientation of the tibia for such relief, however, requires thorough study of the leg structure to determine the shape and orientation of the segment to be removed, and removal of a segment of precisely the predetermined shape and orientation. Otherwise any relief obtained may be only temporary.
One prior art osteotomy guide for use in removing such a segment guides the path of a saw that cuts the wedge-shaped segment from a guide structure attached to the side of the tibia. Such a guide is bulky and thus difficult to precisely locate, however; and affords no positive way of checking after it is attached to be sure that the wedge that will be removed by its use will be removed precisely from the desired location on the tibia.
Another prior art osteotomy guide for use in removing such a segment comprises two guide pins, including a first pin adapted to be inserted into the tibia just below and generally parallel to the plane of the knee joint, and a second pin adapted to be inserted into the tibia at an angle with respect to the first pin corresponding to the dihedral angle of the wedge-like segment desired to be removed. The surgeon guides the flat surface of an oscillating saw along the adjacent surfaces of the pins to cut the wedge-shaped segment from the tibia. The location of such guide pins can be checked by X-ray devices to be sure that they are accurately placed. Each pin makes only line contact with a planar side surface of the saw that it guides, however, so that the saw can cut along a number of different planes tangent to the surface of each pin, each of which planes will result in a slightly different dihedral angle for the segment removed, and a different orientation of the line of intersection of the cutting planes that define the hinge line about which the tibia is bent after the segment is removed. Thus it is easily possible to cut out and remove a segment that affords more or less correction than is desired, and that results in the tibia being bent in a sagittal plane as well as a longitudinal plane of the body, which may not be a desired result.